Terrestrial Time (TT) is a modern astronomical time standard defined by the International Astronomical Union, primarily for time-measurements of astronomical observations made from the surface of the Earth. For example, the Astronomical Almanac uses TT for its tables of positions (ephemerides) of the Sun, Moon and planets as seen from the Earth. In this role, TT continues Terrestrial Dynamical Time (TDT), which in turn succeeded ephemeris time (ET).

The unit of TT is the SI second, the definition of which is currently based on the caesium atomic clock, but TT is not itself defined by atomic clocks. It is a theoretical ideal, which real clocks can only approximate.

TT is distinct from the time scale often used as a basis for civil purposes, Coordinated Universal Time (UTC). TT indirectly underlies UTC, via International Atomic Time (TAI).

Sometimes times described in TT must be handled in situations where TT's detailed theoretical properties are not significant. Where millisecond accuracy is enough (or more than enough), TT can be summarized in the following ways:

John Towner Williams (born February 8, 1932) is an American composer, conductor, and pianist. In a career spanning almost six decades, he has composed some of the most recognizable film scores in the history of motion pictures, including the Star Wars saga, Jaws, Superman, the Indiana Jones films, E.T. the Extra-Terrestrial, Hook, Jurassic Park, Schindler's List, War Horse, Home Alone and the first three Harry Potter films. He has had a long association with director Steven Spielberg, composing the music for all but two (Duel and The Color Purple) of Spielberg's major feature films.

Other notable works by Williams include theme music for four Olympic Games, NBC Sunday Night Football, the NBC Nightly News, the rededication of the Statue of Liberty, and the television series Lost in Space. Williams has also composed numerous classical concerti, and he served as the principal conductor of the Boston Pops Orchestra from 1980 to 1993; he is now the orchestra's conductor laureate.

Williams has won five Academy Awards, four Golden Globe Awards, seven BAFTA Awards, and 21 Grammy Awards. With 47 Academy Award nominations, Williams is the second most nominated person, after Walt Disney. John Williams was honored with the prestigious Richard Kirk award at the 1999 BMI Film and TV Awards. The award is given annually to a composer who has made significant contributions to film and television music. Williams was inducted into the Hollywood Bowl Hall of Fame in 2000, and was a recipient of the Kennedy Center Honors in 2004.

Jill Cornell Tarter (born Jan 16, 1944) is an American astronomer and the outgoing director of the Center for SETI Research, holding the Bernard M. Oliver Chair for SETI at the SETI Institute.

Tarter received her undergraduate education at Cornell University, where she earned a Bachelor of Engineering Physics Degree, and a Master's degree and PhD in astronomy from the University of California at Berkeley.

Tarter has worked on a number of major scientific projects, most relating to the search for extraterrestrial life. As a graduate student, she worked on the radio-search project SERENDIP, and created the corresponding backronym, "Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations." She was project scientist for NASA's High Resolution Microwave Survey (HRMS) in 1992 and 1993 and subsequently director of Project Phoenix (HRMS reconfigured) under the auspices of the SETI Institute. She was co-creator with Margaret Turnbull of the HabCat in 2002, a principal component of Project Phoenix. Tarter has published dozens of technical papers and lectures extensively both on the search for extraterrestrial intelligence and the need for proper science education. She is credited with coining the term "brown dwarf" for the classification of stars with insufficient mass to sustain hydrogen fusion. She has spent 35 years in the quest for extraterrestrial life and announced her retirement in 2012.

Seth Shostak (born July 20, 1943) is an American astronomer. He grew up in Arlington, VA and earned his physics degree from Princeton University and a Ph.D. in astronomy from the California Institute of Technology.

He is the Senior Astronomer at the SETI Institute in Mountain View, California, and the 2004 winner of the Klumpke-Roberts Award awarded by the Astronomical Society of the Pacific in recognition of his outstanding contributions to the public understanding and appreciation of astronomy.

Before his involvement with SETI research, he used radio telescopes in the USA and the Netherlands, searching for clues to the ultimate fate of the universe by analyzing galaxy motion.

In addition to his experience as an active participant in SETI research, Shostak is also involved as a science educator. He presented twelve 30-minute lectures on audio-tape and video titled "The Search for Intelligent Life in Space" for the Teaching Company in 1999.

Since February 2002 Shostak has hosted the SETI Institute's radio program Are We Alone? which was renamed "Big Picture Science" in July 2011. Each week, Shostak interviews guests about the latest scientific research on a variety of topics: cosmology, physics, genetics, paleontology, evolutionary biology and astrobiology. Big Picture Science is distributed on the Public Radio Satellite System and the Public Radio Exchange and is available for download at the SETI Institute's website and through podcasts.

James David Head is a Canadian television director.

Head began his career as a cameraman on various film crews. In 1985, he was a second assistant camera for the concert film 9012Live by Yes. In 1987, he was a second assistant camera for the movie Stakeout. He then worked as a first assistant camera on Beyond the Stars (1989), The Fourth War (1990), Run (1991), And the Sea Will Tell (1991), and Bingo (1991).

Head made his directorial debut in 1991, directing at least one episode of TV's The Commish, but did not become a full-time director at that time. He was second unit director of photography for Man of the House (1995) and Fear (1996). He was back as a director in 1996, directing at least one episode of F/X: The Series. In 1997, he directed an episode of The Adventures of Sinbad, and during the 1996-97 season, he has directors credits for three episodes of Two. During the 1998-99 TV season, he directed two episodes of The Crow: Stairway to Heaven, an episode of Nothing Too Good for a Cowboy, an episode of Poltergeist: The Legacy, and five episodes of Earth: Final Conflict. Between 1998 and 2001, he directed six episodes of The Outer Limits . In 2000, he was second unit director on First Target and he directed a television movie remake of The Spiral Staircase. In 2001, he was second unit director on Just Cause and also directed at least one episode of Wolf Lake. In 2002, he was second unit director for two episodes of Jeremiah and then went on to direct two episodes of the series.